Tobacco composition

ABSTRACT

A smoking preparation comprising tobacco and a zeolite material which effects a decrease in the amount of polycyclic aromatic compounds produced from the pyrolytic reactions of tobacco, the zeolite material being of the Y-type structure, at least partially exchanged with zinc ions and containing platinum or silver.

United States Patent Norman et al.

151 3,703,901 [451' Nov. 28, 1972 TOBACCO COIVIPOSITION [72] Inventors: Vello Nonnan, Chapel Hill; Thomas B. Williams, Durham; Andrew G. Kallianos, Durham, James D. Mold, Durham, all of NC.

[73] Assignee: Liggett & Myers Incorporated, New

York, N .Y.

[22] Filed: March 11, 1971 [2]] App]. No.: 123,422

' Related US. Application Data [63] Continuation-impart of Ser. No. 749,324, Aug.

1, 1968, Pat. No. 3,572,348.

[52] US. Cl. ..13l/17 R,'131/262A- [51] Int. Cl. ..A24b 15/02 [58] Field of Search ..13l/262, 17

[56] References Cited UNITED STATES PATENTS 3,251,365 5/1966 Keith et al. ..l31/l0.7 3,266,973 8/1966 Crowley l 3 1/262 UX 3,572,348 3/1971 Norman et a1.....-....l3l/262 A Primary ExaminerMelvin D. Rein Attorney-Kenyon & Kenyon Reilly Carr & Chapin [57] ABSTRACT 12 Claims, No Drawings TOBACCO COMPOSITION- This application is a continuation-in-part of our copending application Ser. No. 749,324, filed Aug. 1, 1968 now Pat. No. 3,572,348.

The invention relates to a tobacco preparation containing crystalline aluminum silicate zeolites and more particularly to such preparations containing specific zeolites as described.

Observations of the mechanism of combustion in tobacco preparations, such as cigarettes indicate that the smoke components responsible for biological activity are formed in the pyrolysis zone of the cigarette cone. It has been suggested that the formation of such smoke components involves free radicals as intermediates. Based upon this concept, it had been proposed that zeolite materials having free radical promoting catalytic activity be used to control or in.- fluence free radical formation in the pyrolysis zone and thereby cause alterations in the structure of the pyrolysis products formed in expectation of a reduction in biological activity. An alternative suggested mechanism involves the participation of ionic species in the reformation process of smoke components. It has also been proposed that zeolite materials which are known to promote carbonium ion activitybe used in an attempt to influence smoke composition.

Tobacco preparations containing zeolite materials are known. For example, U.S. Pat. No. 3,292,636 discloses tobacco preparations in combination with crystalline zeolite molecular sieves such as the L, X, Y or synthetic mordenite types, or naturally occurring faujasite materials, which sieves may contain any metal having a vapor pressure below 1 atmosphere at l,000C and possessing catalytic activity for organic conversion. Such materials are said to result in tobacco preparation wherein vaporized and at least partially oxidized, but unidentified irritant materials, are rendered less irritable to the smoker while the tobacco preparation is being consumed.

in out copending application Ser. No. 749,324, above mentioned thereis disclosed a smoking composition comprising tobacco in association'with a Y zeolite which is at least partially exchanged with zinc ions and may also contain catalytically active palladium.

It has now been found that Y-type crystalline zeolite molecular sieves having pores sufficiently large to receive benzene, at least partially exchanged with zinc and containing some other metals or ions also have an ability to significantly decrease the amounts of certain polycyclic aromatic hydrocarbons which are noi mally produced from tobacco upon pyrolysis.

Accordingly, it is an object of this invention to provide a smoking preparation which on burning substantially reduces the level of polycyclic aromatic compounds in smoke.

Other objects will be apparent from the disclosure and appended claims.

According to this invention, a novel smoking preparation is provided which comprises tobacco, and a zeolite composition consisting essentially of a Y-type crystalline zeolite molecular sieve having pores sufficiently large to receive benzene and at least partially exchanged with zinc and containing platinum or silver. The platinum is incorporated in finely divided form in the inner adsorption region of the molecular sieve. The silver can be exchanged onto the molecular sieve material. Both the platinum and the silver are used in quantity sufficient to constitute between about 0.05 percent and 15 percent by weight of the catalyst composition. At least 0.05 weigh percent metal is required to obtain some catalytic conversion of the vaporized organics and more than 15 percentmetal does not appreciably improve the effectiveness of this conversion. A range of from about 0.1 percent .toabout l0 percent by weight of the added metal or ion is a preferred balance of these characteristics. The catalytic composition can be added to tobacco by dispersing it uniformly as particles smaller than about 100 mesh orit can be incorporated as an ingredient in the manufacture of reconstituted tobacco sheet. The catalyst composition comprises at least 0.5 percent by weightand up to about 50 percent and greater by weight of the smoking preparation. At least 0.5 weight percent catalyst composition is needed .to effect some degree of adsorption and catalytic conversion of the vaporized organics. Quantities in excess of about 50 percent do not effect a significant increase in reduction iii'the yield of polycyclic aromatic hydrocarbons produced'in pyrolysis reactions from the tobacco mixture. A range of about from 1 percent to about 35 percent by weight catalyst composition in the smoking tobacco preparation represents a preferred balance of these requirements. Proportions significantly greater than about 40 percent are commercially impractical. The catalyst composition is uniformly dispersed in the tobacco so that it is present in the zones of burning, preheating and the region of substantially ambient temperature.

As to the particular crystalline zeolite molecular sieves, they may be described as being of the Y-type, consisting of an open three-dimensional frameworkof SiO, and A10 tetrahedra which are cross-linked by the sharing of oxygen atoms, so that the ratio of oxygen atoms to the total of the aluminum and silicon atoms is equal to two, or 0/(Al+Si)=2. The negative electrovalence of tetrahedra containing aluminum is balanced by the inclusion within the aluminum silicate framework of cations, for example, alkali metal, and alkaline earth metal ions such as sodium, potassium, calcium, and magnesium ions. 0 One cation may be exchanged for another by ion exchange techniques. The void spaces in the framework are occupied by water molecules.

Type-Y zeolite may be represented by the formula:

0.9i0.2Na 0:Al O :xSiO :yI-l,O wherein x is a value greater than 3 up to about 6 and y may be a value of to about 9. Zeolite Y has pores of about 10-13 angstroms size, and is described in U.S. Pat. No. 3,130,007.

Component Wt.% (anhydrous basis) SiO, 62.8 Al O, 2l .6 Na,0 1.5 ZnO 14.6

The oxide molar ratios of such a molecularsieve would be:

SiOJAhO,

4.9 Nu,O/Al,0, 0.12 zno/A|,0, 0.85

' molecule. If a relatively small pore molecular sieve were employed, the large molecules of organic vapors would be blocked by the pores-and could not pass into the inner adsorption region of the molecular sieve. Since the surface area of this inner region is about one hundred times the external surface area the molecular sieve would be largely ineffective for both adsorption and contact between organic vapors and the catalytically active metal.

The catalyst composition should bewell dispersed through the tobacco so that it will be uniformly effective during the entire smoking of the preparation. For this reason, it is employed as a fine powder of particle size smaller than about 100 mesh. Also, the fine powder form eliminates the need for a tobacco-catalyst composition binder which would be needed if the latter were introduced as relatively large particles. The powder may be added to the tobacco at any of several points in the tobacco processing operation. For instance, it may be dusted into the tobacco leaves entering the shredding machine or it may be added after the tobacco leaves have been shredded and clarified of stem pieces and other debris. Alternatively, the catalyst composition may be introduced along with other additives, such as humectant or flavoring which are also added in a manner to assure uniform dispersion in the EXAMPLE 1 20 lbs. of Y-type zinc exchanged molecular sieve containing about 14.6 wt.% zinc expressed as ZnO and 0.51 wt.% platinum was added to a mixture of 140 lbs. of ground strip blend, 12.4 lbs. of Solka Floc a -cellulose) and 6.5lbs. of sodium carboxymethyl cellulose. This combination was dry-mixed for one hour in a double cone blender and then wet-mixed in a paddle mixer with 1.08 gal. of glycerine, 0.33 gal. of propylene glycol and 8 gal. of water. The resulting damp mixture was processed in conventional reconstituted tobacco making equipment at the rate of 600 lbs/hour. The resulting sheet, at 12 percent moisture level, was cut at 32 cuts/inch.

- A second sample made from tobacco sheet containing Y-type zinc exchanged molecular sieve containing about l4.6 wt.% zinc (as zinc oxide) and 2.9 percent silver was fabricated and cut at 32 cuts/inch. Tobacco sheet containing Y-type zinc exchanged molecular sieve containing 14.6 percent zine (as zinc oxide) was fabricated and cut into 32 cuts/inch, and used as the third sample. The fourth sample was a control sheet containing no molecular sieves and was fabricated and cut in the same fashion.

All foursamples were pyrolyzed in a special pyrolysis reactor. This reactor consists of a steel cylinder about 4 I inches in diameter and inches long with annular space at the central perimeter covered with a stainless steel,

TABLE 1 Reduction in the Yield of PCAH fraction per 1000 g of Tobacco Pyrolyzed Sample No.

4 control 3 Zn Y 27. 1% 2 Ag (3%)Zn"Y 29.7% l Pt(0.5%)Znf'Y 40.2%

It is observed thatthe yield of polycyclic aromatic hydrocarbons decreased in yield relative'to the control by at least about 29 percent.

It will be understood that it is intended to cover all changes and modifications of the descriptive examples of the invention wherein chosen for the purpose of illustration which does not constitute departures from the spirit and scope of the invention. It is further understood that the Abstract of Disclosure is included in this specification solely for thepurposes of Rule 72(b) of the Rules of Practice of the United States Patent Office.

We claim:

1. A smoking preparation comprising:

a. tobacco; and

- b. Y type zeolite material at least partially zinc exchanged wherein said zeolite: contains catalytically active material selected from the group consisting of platinum and silver 2. The preparation of claim 1 wherein the platinum contained in said zeolite is in finely divided form in the inner adsorptive region of said zeolite.

3. The preparation of claim 1 wherein the silver is exchanged onto the zeolite material.

4. The preparation of claim 1 wherein the proportion of said catalytically active material contained in said zeolite is in the range of between about 0.05 and 15 percent by weight of said zeolite.

5. The preparation of claim 1 wherein the proportion of said zeolite is at least about 0.5 percent by weight of said preparation.

9. The preparation of claim 1 wherein said zeolite is uniformly dispersed in said tobacco as particles smaller than about mesh.

10. The preparation of claim 1 wherein said preparation is a cigarette.

11. The preparation of claim 1 wherein said preparation is a cigar.

12. The preparation of claim 1 wherein said preparation is pipe tobacco. 

2. The preparation of claim 1 wherein the platinum contained in said zeolite is in finely divided form in the inner adsorptive region of said zeolite.
 3. The preparation of claim 1 wherein the silver is exchanged onto the zeolite material.
 4. The preparation of claim 1 wherein the proportion of said catalytically active material contained in said zeolite is in the range of between about 0.05 and 15 percent by weight of said zeolite.
 5. The preparation of claim 1 wherein the proportion of said zeolite is at least about 0.5 percent by weight of said preparation.
 6. The preparation of claim 1 wherein the proportion of said zeolite is in the range of between about 0.5 and 50 percent by weight of said preparation.
 7. The preparation of claim 1 wherein the proportion of said catalytically active material contained in said zeolite is in the range of between about 0.1 and 15 percent by weight of said zeolite.
 8. The preparation of claim 1 wherein the proportion of said zeolite is in the range of between about 1 and 35 percent by weight of said preparation.
 9. The preparation of claim 1 wherein said zeolite is uniformly dispersed in said tobacco as particles smaller than about 100 mesh.
 10. The preparation of claim 1 wherein said preparation is a cigarette.
 11. The preparation of claim 1 wherein said preparation is a cigar.
 12. The preparation of claim 1 wherein said preparation is pipe tobacco. 